1. Field of the Invention
The present invention relates to an inorganic-organic hybrid polymer composed of nano-particles on the surface using dendrimers and a manufacturing method thereof. More particularly, the invention directs itself to an inorganic-organic hybrid polymer composed of nano-particles on the surface using dendrimers and a manufacturing method thereof, in which nanometer-sized inorganic (metal) particles are uniformly dispersed across the surface of the polymer and available as optically, electrically and magnetically functional materials.
2. Description of the Related Art
In general, nanometer-sized metal or semiconductor particles; i.e., nano-particles having a nonlinear optical effect, and composite materials composed of the nano-particles dispersed on a polymers or a glass matrix, have attracted people""s attentions in optically functional materials.
Moreover, nano-particles having a magnetic property are applicable in various ways, for example, electromagnetism storage media. One method for manufacturing the composite materials involves applying a monolayer of the nano-particles, produced by vacuum deposition, sputtering, chemical vapor deposition (CVD) and sol-gel process, on a suitable support film.
For example, a method for manufacturing a self-assembly monolayer is well known in which 3-mercaptopropyl trimethoxysilane or 3-aminopropyl trimethyoxysilane is adhered to the surface of a glass substrate with silane (SiH4) and impregnated into a solution containing nano-particles (Ref. Doron A., Katz E., Willner I. Langmuir, 1995, 11, 1313; Graber K. C., Freeman R., Hommer M. B., Natan M. J., Anal. Chem. 1995, 67, 735; and Freeman R. G., Grabar K. C., Allison K. J., Bright R. M., Davis J. A., Guthrie A. P., Hommer M. B., Jackson M. A., Smith P. C., Walter D. G., Natan M. J., Science, 1995, 267, 1629).
A conventional nano-particle-dispersed matrix system has unsatisfactory characteristics as a composite material, for example, it causes light scattering when used for nonlinear optics, because the nano-particles are ready to change state due to their high surface energy and form an agglutinate during dispersion in the matrix.
A dendrimer is a nanometer-sized monodisperse polymer featuring a tree-like or generational structure that is prepared a from at least one monomer having branching points therein. Known is a method for chemically adhering dendrimers on the surface of polymers using the functional terminal groups (Ref. Korean Patent Appln. No. 10-2000-42435 by WON Jongok, KANG Yong Soo, PARK Yong Soon, CHA Bong-Jun, PARK Hyun-Chae, and Jung Bum-Suk).
Fine particles are different in characteristics from bulk particles due to the finite size effect. For forming the fine particles, many attempts have been tried to produce nanometer-sized metal particles having a zero valence that are stable under various physical and chemical synthesis conditions and susceptible to monodispersion.
Conventional attempts include the techniques of sputtering, metal deposition, abrasion, reduction of metallic salts, and decomposition of organometal precursors.
Transition metal particles, such as gold (Au), silver (Ag), palladium (Pd) and Platinum Pt), manufactured by conventional methods, are in the form of an aggregated powder state or are sensitive to air and tend to be agglomerated irreversibly.
Such an air sensitivity raises a problem in stability when the metal particles present are in a large amount. Moreover, the air sensitivity has another problem that the metal particles are oxidized if the final products are not sealed under a high-priced air blocking state during the manufacturing process.
The irreversible agglomeration raises a separation problem which causes a broad particle size distribution and prevents formation of a smooth and thin film, which is essential for the magnetic recording application field. The agglomeration reduces surface area, which is chemically active for catalytic action, and largely restricts solubility, which is essential for biochemical label, separation and chemical delivery processes.
To control particle size or to manufacture mono-dispersed nano-particles is an important object in a technical application field of the nano-materials. Therefore, control of the nano-particle""s sizes and size distribution is the main concern in both physical methods, such as mechanical abrasion, metal deposition condensation, laser ablation and electrical spark corrosion, and of chemical methods such as reduction of metallic salt in a solution state, pyrolysis of metal carbonyl precursor and electrochemical plating of metals.
It is impossible to improve the existing process of direct dispersion of nano-particles into the matrices, since several physical or chemical methods cause imcompatibility and permanent agglomeration. These problems arise during the composite process when metal particles are accumulated from a vapor state under the existence of appropriate stabilizer, or from a transfer fluid or a transfer fluid containing the stabilizer.
Furthermore, even though the metal particles are manufactured in a mono-dispersed state, the particles are agglomerated and not well dispersed due to the heat or pressure generated during the process of dispersing the metal particles in the polymer matrix, especially when the metal particles are not compatible with the polymer matrix and defects are generated on the interface.
It is, therefore, an object of the present invention to provide inorganic-organic hybrid polymers composed of nano-particles on the surface using dendrimers and a manufacturing method thereof, in which inorganic nano-particles are uniformly dispersed on the surface of the polymer material without a permanent agglomeration.
It is another object of the present invention to provide a simple method for adhering inorganic nano-particles on the surface of polymers with a high adhesive strength using dendrimers.
It is further another object of the present invention to provide a method for easily adjusting the size of inorganic particles and the distance between the nano-particles on the surface of polymers based on the amount of metal precursors or dendrimers.
To achieve the above objects, there is provided a method for manufacturing an inorganic-organic hybrid polymer composed of nano-particles on the surface using dendrimers, the method including the steps of: (a) forming a functional anhydride group on a polymer-based matrix; selectively adding one of metals and inorganic salts to the dendrimers to prepare either a dendrimer-metal precursor solution or a dendrimer-inorganic particle solution; (b) inducing the reaction between the functional anhydride group of the surface of polymer matrix with the solution to form a chemical bond between the matrix and the dendrimer; and (c) reducing the metal ions or inorganic particle by irradiation of light.
The metal precursor is used herein is at least one metallic salt selected from a group consisting of Au, Pt, Pd, Cu, Ag, Co, Fe, Ni, Mn, Sm, Nd, Pr, Gd, Ti, Zr, Si; or an intermetallic compound of elements, binary alloy of elements, ternary alloy of elements, and Fe oxide, barium ferrite or strontium ferrite.
The matrix used in the present invention is a polymer film having anhydride functional groups formed by plasma treating of the polymer films in the existence of maleic anhydride.
The matrix as used herein can be chosen from any polymer film in engineering polymers or specialty polymers, having anhydride groups on the surface formed by plasma treatment.
Examples of the polymer are polypropylene, biaxial orientation polypropylene, low-density polyethylene, high-density polyethylene, polystyrene, polymethyl methacrylate, polyamide 6, polyethylene terephthalate, poly-4-methyl-1-pentene, polybutylene, polypentadiene, polyvinyl chloride, polycarbonate, polybutylene terephthalate, polydimethylsiloxane, polysulfone, polyimide, cellulose, cellulose acetate, ethylene-propylene copolymer, ethylene-butene-propylene terpolymer, polyoxazoline, polyethylene oxide, polypropylene oxide, polyvinylpyrrolidone, and derivatives thereof.
A general mechanism of the present invention is illustrated in the drawings of FIGS. 1a to 1f. 
Anhydride functional groups has been introduced on the polymer surface by plasma treatment when the polymer film and maleic anhydride were located in the plasma reactor, (step 1; see FIG. 1a, product 1).
An appropriate amount of metal or inorganic salt is added to a dendrimer-containing solution to prepare a dendrimer-metal precursor solution (step 2; see FIG. 1b, product 2) or a dendrimer-inorganic particle solution (step 3; see FIG. 1c, product 3) by the interaction between the dendrimer and the metal or inorganic salt.
The dendrimer-metallic salt/inorganic particle complex solution is brought in contact with the polymer matrix having the anhydride groups to cause a chemical reaction (steps 4 and 5; see FIGS. 1d and 1e, products 4 and 5, respectively).
Subsequently, the polymer film in which the dendrimer containing the metallic salt is adhered to the surface of the polymer matrix (product 4) is subjected to UV radiation to reduce metallic salt and thereby prepare an inorganic-organic hybrid polymer film with uniformly dispersed nano-particles (step 6; see FIG. 1f, product 6).
The hybrid polymer of the present invention can be used as a component for controlling the phase, strength or frequency of light. This is known as the characteristic of the nanometer-sized metal hybrid polymers having no agglomeration. Such a hybrid polymer can also be used as a data storage medium using the magnetic property of the metal nano-particles.
The hybrid polymer of the present invention also has physical and chemical activities to the subsequent reactions due to the existence of the functional dendritic polymer on the surface.
Furthermore, regulating the property of the matrix allows the use of the hybrid polymer in various applications utilizing the nonlinear optical effect of the metal nano-particles and the characteristics of the matrix (for example, electric conductivity). If the metal nano-particles have catalytic activity, the hybrid polymer may be used as a catalyst of which a catalytic component is supported by a heat-resistant matrix.